The Houston Astros entered the month of May with six or possibly seven candidates to select with their No. 1 overall pick in the First-Year Player Draft.

Now, with mere hours remaining before the Draft begins on Thursday night, there hasn't been much change in the situation, as five prospects are being discussed in Houston's Draft room. At least the Astros can't say they didn't warn anyone.

"I don't think we're going to have any dramatic narrowing until the end," Mike Elias, the Astros' director of amateur scouting, said nearly a month ago. "I think it's important to keep scouting them until the very end. We're making sure we're keeping the field as open as we can. We are not going to make that decision when there's no reason to."

There will be reason to soon enough. The Draft begins with the Draft preview show on MLB.com and MLB Network on Thursday at 6 p.m. ET. Live Draft coverage from MLB Network's Studio 42 begins at 7 p.m., with the Astros starting things off and the top 73 picks being streamed on MLB.com and broadcast on MLB Network. Rounds 3-10 will be streamed live on MLB.com on June 7, beginning with a preview show at 12:30 p.m., and Rounds 11-40 will be streamed live on MLB.com on June 8, starting at 1 p.m.

MLB.com's coverage includes Draft Central, the Top 100 Draft Prospects list and Draft Tracker, a live interactive application that includes a searchable database of Draft-eligible players. You can also keep up to date by following @MLBDraft on Twitter. And you get into the Draft conversation by tagging your tweets with #mlbdraft.

For some time now, most have believed the two main candidates to go No. 1 overall are the two best college pitchers, Stanford's Mark Appel and Oklahoma's Jonathan Gray. Appel and Gray separated themselves from the rest of the class earlier this year and have more or less maintained their spots at 1 or 2 on the Top 100.

Appel was a potential No. 1 pick a year ago, fell to the Pirates at No. 8 but returned to Stanford for his senior season rather than sign with Pittsburgh. He had a better season as a senior and it seems likely he will hear his name called in one of the first few picks. The Astros didn't take him last year, though, leading many to believe they won't select him this time around, either.

Unlike Appel, whose season is over, Gray is still pitching. Thanks in part to his strong NCAA regional start, the Sooners are preparing for Super Regional play against Louisiana State. Gray doesn't have the track record that Appel has had over the years, but he's been every bit as good, if not better, than his Stanford counterpart in 2013. While many scouts don't think that the recent news of Gray's positive test for the ADHD drug Adderall will impact his status much, it remained to be seen if it has altered Houston's opinion of him.

With no clear-cut No. 1 overall pick in this year's Draft class, we profile each candidate who could go 1-1.

North Carolina third baseman Colin Moran was seen as more of a dark horse a month ago, but talk of him potentially going first continues to persist. Moran, who's Tar Heels are also playing in a Super Regional this weekend, has had an outstanding season, hitting .348 with 13 homers and 86 RBIs and being named a Golden Spikes Award finalist. Should he go No. 1, though, it would likely be a signal that the Astros decided to save money at the top and perhaps be aggressive later on, as they did in 2012 when they took shortstop Carlos Correa of Puerto Rico with the first pick.

San Diego's Kris Bryant is also a Golden Spikes finalist, thanks to his 31-homer season. He's performed well in his entire college career, including for Team USA, and his power is legitimate. He's become a much better all-around hitter than he was in high school and the big home run total masks the fact that he's highly athletic and has good overall tools. He has more than enough ability to remain a third baseman, but a team could easily move him to right field and he'd fit there very well, considering his power and plus arm. While there has been more buzz about Moran than Bryant in discussions regarding the top picks, in some ways it is Bryant who better fits the profile of a No. 1 overall pick.

That leaves one high schooler. At one point, both of the top Georgia high school outfielders, Clint Frazier and Austin Meadows, were said to be in the mix. It seems more and more likely that the top pick on Thursday will be a collegian, but it appears that Frazier and his plus bat speed are still being discussed.

The one player from the initial pool of candidates no longer in the mix is Sean Manaea, a lefty from Indiana State. Manaea entered the spring very much in there with Appel and Gray. But the he never was quite as dominant as he was last summer in the Cape Cod League. A hip flexor injury threw him off and caused his stuff to back up. In what would have been his final start of the season, Manaea threw three warmup pitches and was scratched as talk of possible shoulder stiffness gave teams something else to worry about.

Jonathan Mayo is a reporter for MLB.com and writes a blog, B3. Follow @JonathanMayoB3 on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.